To date, we have screened 46 patients as candidates for treatment with naltrexone. These patients have been recruited from the detoxification program at the hospital. Of these, some 26 have actually started on a naltrexone treatment program but the rate of retention has been exceedingly poor. Eight patients took only a single dose and abandoned the program; 3 remained in treatment up to a week; 5 remained in treatment up to a month. Only 9 patients have been treated for more than one month. Although these figures look to be dismal, they represent the type of experience that others have had. The fall-off between selection for study and beginning treatment is high, as is the loss of patients once started. Our goals in the coming year will be to increase our experience in regard to the number of patients treated and the duration of treatment. We hope to be able to assess better those patients who are the most likely candidates for treatment. We expect to experiment with different dosage schedules, to determine which is best tolerated and most quickly leads to complete blockade with a minimum of clinic visits. We shall recruit patients who have been withdrawn from methadone programs as well as those about to be discharged from or who are about to enter drug-free treatment programs.